Subwoofer suggestions needed

Current setup: 2011 Hyundai sonata stock stereo, all door speakers stock. Will upgrade later. Using kicker 300.1 with kicker l3 12" sub in ported custom box. Received a planet audio 2400.1 in trade today. Looking for sub to use with this amp. So not want another box taking up entire trunk again so smaller is better. Plan to custom a box. Dimensions can hopefully be 14 high 29 wide 14 deep at bottom and 7 deep at top. Odd numbers but this will fit my needs. Can add depth and build up the facing if needed. So down to question:

Music: Mostly rap some rock. Decaf and remixes. Car going to son next year (12th grader) for college.
What sub to match BB2400.1 planet audio amp?
Budget $350 or less. Will continue to save if its not possible at that price.

Re: Subwoofer suggestions needed

thats a powerful amp for your budget probably american bass xfl but those will be over your budget, you can get the c2 audio for $109 per sub and its pretty beefy, 3 of those should hanldle that amp and you will be under $350